Posture & Performance

This is a little article I wrote recently for my newsletter. I'm making more of an effort to contribute meaningfully to the PT Forum, so I thought I'd post it here as a thread for anyone who might find it interesting. A little warning though, it's kind long, like 1500 words.

Originally, I was asked to explain how posture, body alignment and core strength affect or improve martial arts ability. But since that is a fairly narrow topic, I’m going to broaden the discussion to how kinetic chain integrity can improve functional sport and daily performance in general. All of the principles will apply to all sport, MAs included.

When I refer to the “kinetic chain”, what I’m really talking about is the body as a whole. More specifically, I’m talking about the aspects of the body that create, control or neutralize movement. Typically, the kinetic chain is broken down into three parts. First is the articular, or skeletal system. Your skeleton is your bones, which provide the central structure and shape for your entire body, as well as provide the anchors or attachments for muscles to pull to create movement in the first place. The word articular simply refers to joints, which are the places where the skeleton can move. Clearly, if the bones couldn’t move, neither could we. Second is the muscular system. The muscles are the engines that create movement. By contracting, lengthening or creating static tension in particular groups or series, the muscles provide force in virtually every direction and in countless combinations. These combinations give us the ability to perform every task from breathing to jumping to juggling while riding a unicycle. The final segment is the nervous system. If the muscles are the engines of our body, then the nervous system is the driver. No action occurs in our body without some kind of input from the nervous system. That being the case, it becomes obvious how important including the nervous system into the overall movement picture is.

Posture is a term that I believe most people underestimate. To most people, the word posture simply refers to the way in which we sit or stand. But, the reality is, it’s much more complicated than that. Posture is the position in which movement begins, occurs and ends. Posture has a static (unmoving) component and a dynamic (moving) component. Both are important, because after all we spend some parts of the day moving and some parts standing still. Your body’s alignment is going to determine the way in which your muscles function and the way in which your joints and skeleton are stressed as well. I will discuss the way in which posture affects the three systems mentioned previously: Articular, Muscular and Nervous, as well as how these relate to human performance.

Your body’s posture is absolutely crucial to the skeletal, or articular, part of the kinetic chain. If, for no other reason, then because the alignment of the body determines how your center of gravity is positioned relative to your base of support. When the center of gravity is properly aligned, your body’s weight as well as the weight of anything attached to it will be evenly distributed among your various bones, joints and connective tissues. This minimizes any excessive wear on specific joints, yet still provides the joints the appropriate bearing of weight that is necessary for ideal joint health. Additionally, proper posture keeps each joint in an ideal position where the related stabilizers are at maximum advantage. Allowing for optimal use of joint stabilizing muscles is obviously going to improve joint safety, but it will also improve joint mobility. Improved stability and mobility together allows for a more functional, more capable body.

The muscular system is the first part of the kinetic chain that most people consider. And like the other parts, it too is affected greatly by bodily positioning. Muscles change length as the body moves in order to accommodate movement. When the body is in ideal alignment, the muscles return to “neutral” position, where they are neither lengthened nor contracted. As the alignment changes, certain muscles lengthen and others contract. Usually this is a voluntary action, such as reaching your arm overhead. But over time, various factors in day to day life can affect the way our body is aligned even when relaxed. The result of this is that certain muscles are lengthened and certain muscles are contracted… and they stay that way. If the posture is not corrected consciously, then these various combinations of lengthening and shortening become chronic, physiological changes. The muscles that are chronically lengthened undergo an overall length change, with the fiber overlap diminishing, in effect pulling the muscle slightly apart. This fiber separation is coupled with a decrease in neural input, having the overall effect of weakening the muscle. It may seem counterintuitive at first, but lengthened muscles experience a sensation of tightness. We usually think of a lengthened muscle as a flexible muscle and therefore not tight. However, in this case, a muscle is lengthened because of a change in its physiology, not an improvement in flexibility. Think of a rubber band stretched to its maximum. It is lengthened, but it is also pulled very tight.

The muscles that are chronically contracted also undergo a similar physiological change. Only this time, it’s the opposite effect. The muscle fibers increase the amount of overlap, shortening the overall length of the muscle. Shortened muscles receive an excess of neural input, and have a reduced capacity to lengthen. Physiological shortening leads to a condition known as hypertonicity (which simply means “too much tension”). The increased tension manifests itself in a number of ways. It can cause muscle soreness and pain (think tension headache) and can lead to the development of muscle adhesions (various forms of knots and spasms). And of course, the reduced ability to lengthen hinders movement. Now for the curveball; shortened muscles are also weak. One would think that it would be opposite, right? But the part to remember is that in order to produce strength, muscle fibers have to change from one degree of overlap to another. If the muscle fibers are already increasingly overlapped, then this change is less possible, and the overall force output is less. The asymmetry between shortened and lengthened muscles, in combination with the overall weakening effect of altered physiology, drag down performance as a whole. Additionally, they lead to unbalanced support at the joint, increasing the likelihood of injury.

Finally, we have the effect on the nervous system. The nervous system is constantly learning and adapting to the state of the body as it currently is. So the muscles that are often shortened receive more neural input, reinforcing their deleterious activity, and eventually leading to them becoming overactive. The lengthened muscles are too often at rest, and lose their neural input, becoming underactive. Overactive muscles, due to their increased neural input, engage too often. They become part of synergies (chains of muscles working together) that they should not play a role in. An example of this is when overactive hip flexors try to take over the role of underactive abdominal muscles in persons with lower-crossed syndrome. Underactive muscles, with reduced neural input, don’t engage at times when they properly should. This leads to what is known as “synergistic dominance”. This is where a synergist muscle (a helper) takes over for an underactive primary agonist and tries to do its job. Simply put, this happens because the primary agonist is not doing its job, so the body has to recruit other muscles instead. This drags down performance, because the primary agonist is going to be the best muscle for the job. Synergists are second fiddles that get thrust center stage. This also creates problems because a synergist muscle is not going to create the same kind of movement as the agonist, so we end up with altered movement patterns. Over time, these movement patterns become ingrained into our “muscle memory”, and can be very hard habits to break. It is imperative that specific efforts are made to break the bad movement habits and rebuild good ones. Otherwise, even if the physiological changes were repaired, the mind will still remember the altered way of moving it had ingrained. Altered patterns of movement are inevitably inefficient, and often are deficient in joint and core stability. That means that your overall ability to perform tasks is reduced, and your risk of injury is increased.

In conclusion, it is clear that your body’s posture – both static and dynamic – is of great importance to the proper functioning of the kinetic chain. Whether it’s the structural integrity of your joints, the physiological function of the muscles or the recruitment ability of the nervous system, the entire system is linked. The good news is all of the problems that poor posture creates can be undone. And by making the necessary improvements to the human movement system, we develop good physiology and learn ideal movement patterns that ultimately increase the entire body’s function. There is much more that can be said on this subject, so I imagine that I will be discussing posture and movement again soon.

Using the stretched rubber band to explain tension in lengthened muscles was a nice analogical extension. After reading this and having a think about it, it helps to understand a "muscle-bound" state, and the detrimental effect that this will have on individual performance.

Furthermore, since muscles have to contract to actually do anything - shortened muscles (that can often LOOK very powerful) are likely not very effective at delivering kinetic force.

Guess whenever we see a 400 lbs bodybuilder, we don't have to be as afraid as we thought ^_^ (specifically backyard bodybuilders with no symmetry and low flexibility)

Though of course, we should still be quite afraid if they haven't eaten their lunch yet.

Great article, Tae.
I learnt more than I thought I'd ever need to know about body mechanics last year, but am slowly beginning to apply that knowledge in my practice as well as my training. You article is great food for thought and a fantastic introduction to the topic.

Guess whenever we see a 400 lbs bodybuilder, we don't have to be as afraid as we thought

Body builders who've built muscles up? Not the same thing as chronic contraction.
(Is that what you meant?)

Both of you are right, really. Syberia's correct, a properly trained and built muscle is not dysfunctional simply because it's large or strong. However, bodybuilders as a group do tend to be pretty imbalanced, largely due to their emphasis on individual muscle groups, and general asymmetry in training. Common example: Bodybuilder who emphasizes chest development to a far greater degree than upper back development. The strength asymmetry eventually imbalances the rotator cuff, and bam, something gives. It's a large part of why the bench press sees a disproportionate number of shoulder afflictions. It's not the exercise, it's the priority.

Both of you are right, really. Syberia's correct, a properly trained and built muscle is not dysfunctional simply because it's large or strong.

:D
Lol, yeah, that's where I was going with that.

Or even inflexible. I train with a guy built like a rugby player, stocky and solid. He's as flexible as a gymnast. It's unnatural. It all depends on how they train. But I agree that those who do train focussing only on single muscle groups will be imbalanced.

Sy, you missed the bit in brackets!!

My sincere apologies. I'm going to go with the excuse that I just had an exam and it didn't go well.